[Loadstone] 2 requests: move point and reconnect

Mikolaj Rotnicki mikolaj-rotnicki at o2.pl
Tue Apr 10 18:44:59 BST 2007


I wonder if the info provided on the disconnection issue refers to "Gps 
clock seems to have stopped ticking..."?

I experienced the message "GPS clock seems.." few times with my newly bought 
Wintec WBT-300 based on Antaris 4 uBlox chipset.

It happened suddnly in normal operation. I wonder what might be reason fr 
that. I also have a Nokia LD-3W - but I did not experience that problem.

What does "Gps clock seems to have stopped ticking..." message mean?
Does it mean  that there is something wrong with GPS module or it's BT 
connectivity?
What exactly (from application point of view) causes LS to show Gps clock 
seems to have stopped ticking.." message?

I also tried WBT-300 with other GPS aplications (AFTrack, TomTom5) and did 
not observe any connection loss.

Are there any LS users haveing Wintec WBT-300 receiver and experiencing same 
problem?

Would it be helpful if I send a log file to the LS developpers?

-----
Mikolaj Rotnicki

----- Original Message ----- 
From: "Shawn Kirkpatrick" <shawn at odyssey.cm.nu>
To: <loadstone at loadstone-gps.com>
Sent: Tuesday, April 10, 2007 3:49 AM
Subject: Re: [Loadstone] 2 requests: move point and reconnect


> I'll try to address both your points. First, I don't think that moving a
> point would help your problem very much. There's at least two factors
> effecting this. The first is the accuracy the point was saved with. The
> second is the accuracy of your gps receiver at the current time. Let's
> assume a perfect point accuracy for the moment and deal with the receiver
> accuracy. There are several conditions that'll effect this, the number of
> satellites, surrounding buildings etc. No matter what you do you'll still 
> be
> subject to the gps drift when standing still. If your receiver is 
> waas/egnos
> capable and you get a differencial gps fix then this drift can go down to 
> as
> low as one metre. Otherwise, around 10 metres of drift is about normal. 
> You
> could test this by standing still and hitting the select key to see how 
> much
> the closest point drifts. Some receivers are better for this than others.
> Taking all this in to account moving a point probably won't fix things 
> much.
> You could move a point 10 metres one way and it might be accurate for that
> moment but then it's just as likely to drift 10 metres the other way 30
> seconds later. When you're on the move this situation should be a lot 
> better
> since the drifting isn't as much of a problem.
> The disconnecting problem could be a bit tricky. The clock tick logic was
> implemented because some receivers when there batteries die can get to a
> point where the receiver isn't sending gps data but can still keep the
> bluetooth connection open. To fix this loadstone will disconnect if it
> hasn't heard from the receiver in over 5 seconds. In normal opperation 
> this
> isn't a problem, normally the receiver will send data once per second. If
> your receiver is getting in to a state where it's sending data slower than
> that then this might be causing it to disconnect. This might also account
> for your accuracy problems if the data isn't caught up to where you 
> actually
> are. Maybe the receiver has some kind of power saving mode? You'd have to
> look up information on that unit to find out if that's the case. If that's
> the case then it would be good to turn that mode off. There's a couple 
> other
> situations where the receiver can be disconnected. The first is during 
> long
> searches with the find point function. This is a bug and at some point 
> that
> searching system is going to get a rewrite to hopefully fix things like
> this. The other reason the receiver can disconnect is if you're in an area
> with a lot of rf interference. This can be an area with a lot of computer
> equipment, other bluetooth devices, or something else generating radio
> interference that knocks out the connection. There's not a whole lot you 
> can
> do in that situation. If the gps disconnects consistantly in an area then
> this is probably the reason. The only thing you might be able to do in 
> that
> case is move the receiver closer to the phone. Another problem could be
> glitches in the bluetooth implementation in your phone or gps receiver.
> Nokia is well known for breaking things in there bluetooth 
> implementations.
> In that case a firmware upgrade for the phone might help.
> As to what can be done to fix this problem, maybe a few tweaks to the 
> timing
> logic, maybe increasing the timeout to 10 seconds might work. I don't 
> think
> trying to write a command to the receiver would be a good idea. If it 
> really
> has disconnected then the program could end up in a long wait trying to
> write resulting in a write failure at the end. If the battery is dying but
> the bluetooth connection is still open then the write might appear to go
> through but have no effect. If the receiver has entered a low power state 
> of
> some kind then a hot start may or may not bring it out of that mode. For
> that case a better solution would be to figure out how to get the receiver
> not to go into that mode in the first place. Trying to reconnect might 
> work
> but presents its own problems. If the gps really is disconnected then you
> end up with a long wait and a connection error. The other problem is it
> seems to take a while for the phone to register the fact that a bluetooth
> connection really is gone. This isn't only happening for loadstone, on my
> n70 this happens for headsets and any other type of bluetooth connection.
> Trying to reconnect during this period results in an error. This seems to 
> be
> phone dependant so would be kind of hard to work around.
> Speaking of commands, you've probably noticed that none of the gps 
> commands
> work with a gps receiver using the mtk chipset. This is a known issue, the
> commands are currently for the sirf chipset. We plan to implement a 
> setting
> to set the chipset so the propper commands will get sent.
>
> On Mon, 9 Apr 2007, R. Neill Hadder wrote:
>
>> Hi guys,
>>
>> A 2-item wish list:
>> 1) it seems like it would be possible to implement a "move current point"
>> feature to help counteract the tendency to be say 10m off when you're
>> walking along setting waypoints and then another 10m off, possibly the 
>> other
>> direction, when you're going back through.  I constantly wish I could 
>> just
>> "fix" a point, literally, when I find myself on the wrong side of the 
>> street
>> from what the unit was reporting should be the case: 3 o'clock is as 
>> likely
>> to really be 9:00 as not, within 12 meters, and only trigonometrically
>> better at greater distances.  I'm sure moving a point x meters in a 
>> cardinal
>> direction or clockface orientation translates into some decimal value of
>> milliseconds in the coordinates.  I have a hunch that a little routine to
>> accept input and make this calculation could double the tracking 
>> accuracy.
>> Discussion welcome.
>>
>> 2) As I noted in my comments on the i-blue 737, there's some fairly 
>> common
>> if not random condition that prompts the gps receiver to stop sending 
>> data
>> to the phone, even though it's still actively tracking umpteen satelites.
>> Loadstone disconnects, but can reconnect within a couple of seconds. I 
>> would
>> like to try a setting that allows loadstone to try an automatic hot start
>> before disconnecting.  Even if it's a low battery or low bluetooth signal
>> issue, this would be helpful.  Invariably, the one time that I really 
>> need
>> it in a high-traffic urban environment, the gps will go out and I am 
>> stuck
>> fiddling with things, possibly for a prohibitive period of time.  Seems 
>> like
>> it's worth a try.  Again, my own experience is with the 6682 and mtk.
>>
>> Gracias.
>> --Neill
>>
>>
>>
>>
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>> Loadstone at loadstone-gps.com
>> http://www.loadstone-gps.com/mailman/listinfo/loadstone
>>
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